Eye cataract surgery can generally be divided into two periods of procedure: the preoperative evaluation, and the actually cataract surgery procedure itself.  While cataracts may be present, eye cataract surgery should not be undertaken unless it is the most viable way to help the patient.  In some cases, the presence of glaucoma or other eye diseases may preclude the necessity of a cataract surgery procedure, since the surgery can offer very little additional aid or have the ability to improve vision to any significant degree. 

Pre-operative examinations are necessary before all eye cataract surgery so that the presence of a cataract can be confirmed, and the determination can be made whether a cataract surgery procedure is yet necessary. Many insurance providers have traditionally required that a cataract have developed to a certain level of visual impairment before they will fund  a cataract surgery procedure. This has changed somewhat, as it often considered better to prevent the deterioration of sight than to stave off potential costs, but nevertheless, it remains that eye cataract surgery needs to be entirely justified before proceeding to the actual procedure. 

In some cases, the presence of other medical conditions may either make eye cataract surgery unnecessary or impossible, or otherwise complicated cataract surgery procedures. Cataracts can often develop over time, and sometimes simultaneously with other degenerative conditions, such as glaucoma, macular degeneration, or retinal tearing. In the case of these conditions, the impairment of sight may be more incumbent on their presence then on  the developing cataract, so eye cataract surgery to remove and replace the lens may offer no actual aid, and thus would not be worth the undertaking.  

Even in situations where a cataract surgery procedure can be beneficial, it must be determined that the any other conditions will not interfere in its successful completion or facilitate further complications. In the case of glaucoma, for instance, additional pressure from inside the eye may cause pressure on the vitreous fluid around the lens, leading to interference when removed.  This pressure can be diminished with medications, but it must be regulated within set parameters before eye cataract surgery can be undertaken safely.  

Before a cataract surgery procedure, the pupil must be able to be dilated to allow for full access to the lens of the eye. If the pupil does not dilate properly when eye drops are applied, then special tactics must be taken during surgery to ensure that the pupil is manually dilated, usually with a mechanical device that will hold it open. 

In the presence of other conditions, cataract surgery procedures often will be forced to become more complicated, and will sometimes have to undertake multiple procedures at a given time. In the case of a retinal detachment (either full or partial), it may be necessary to do both the retina reattachment and the eye cataract surgery during the same session, which requires extended time, more complicated cataract surgery procedures, and likely longer and more precise periods of recovery. Similarly, for patients with glaucoma, eye cataract surgery can be combined with a trabulectomy, which relieves interocular pressure from certain forms of glaucoma, which allows for cataract surgery procedures to move forward unhindered. 

The most common form of cataract surgery procedure is phacoemulsification, where the cataract infected lens is emulsified (turned into particles which do not distribute into the liquid) and then withdrawn through a small opening to the side of the cornea.  Afterward, a new interocular lens in inserted into the eye. Cataract surgery of this kind may seem pretty straightforward, but it is a complicated process with a number of important steps in order for it to be completed properly. 

First and foremost, the pupil will be dilated to allow visual access to the interior of the eye so that the interocular lens may be placed behind the iris (some eye cataract surgery places the lens elsewhere due to various complications, but most new lenses are places behind the iris, so that this is the example which will be used here).  The surgeon will then usually apply topical anesthesia in the form of eye drop directly to the eye.  In some cases this will be the extent of the anesthetic employed, but very often more will be applied later on.  When the eye is numb from the initial anesthesia the surgeon will used an object called a lid speculum that holds the eyelid open and allows for continued access to the eye without worrying about the involuntary blinking reflex of the patient. 

Often for cataract surgery procedures the surgeon will inject additional anesthetic to the eye to allow for more complete insensitivity of the surrounding area (these injections are typically painless due to the earlier drops). Occasionally sedatives may be given to the patient to handle anxiety or awkwardness from the procedure (which they will otherwise be completely conscious for).  General anesthetic is typically not used save for extremely particular situations, such as when a child, senior citizen, mentally handicapped, or otherwise anxious person requires eye cataract surgery. Generally speaking, the procedure is usually entirely painless, though there are sometimes feelings of pressure or discomfort from the bright lights pouring into the eye. 

During eye cataract surgery, the patient is usually on a stretcher or an reclining chair.  The eyelids and surrounding portions of the face are swabbed with disinfectant.  The face is covered with a large cloth that leaves exposure only to the eye that is being operated on (it understandable makes the patient less anxious when they cannot see the eye cataract surgery in process). While being propped open during the cataract surgery procedure by the lid speculum, the eye is continuously re-hydrated by saline eye drops or some other substance. 

After the eye has been rendered in-sensory to pain and the patient in the proper position, the cataract surgery procedure can begin in earnest. First, a small incision will be made in the cornea of the eye (usually where the two portions intersect, as it is easier to "hide" the incision there.)  The incision is typically tiny: less than 1.5 mm on average.  This allows for minimal, if any, suturing, and allows for a quicker recovery time. In phacoemulsification, a small opening will instead be made, called a capsulorhexis, which is an opening that allows for easier emulsification. Often a viscoelastic substance will be injected into the eye behind the natural lens that maintains the internal pressure of the eye from becoming destabilized. 

In phacoemulsification, a sonic device is used to destroy the lens, and cause it break up into fragments, which are then aspirated through the capsulorhexis.  In other cataract surgery procedures, the lens is removed by internal incision and removal.  After the cataract has been removed, the new interocular lens is inserted through the small incision commonly rolled up in a large cylinder.  Inside the eye, is is unfurled behind the iris so that it fits into the area where the natural lens had previously resided. 

After the lens has been put in place, the surgeon will make sure that the incision is not leaking fluid, as this could lead to post-eye cataract surgery infections and complications.  If the eye is leaking fluids, suturing may be necessary, but with most phacoemulsifications, the hole is small enough that it sill be allowed to heal on its own provided there are no other complications.  The cataract surgery procedure usually culminates with the surgeon applying drops containing steroids and antibiotics, which facilitate the healing process,  and then place a shield and/or patch over the eye to protect it from strait or infection. 

Most patients who receive eye cataract surgery go home the same day, but have strip requirements placed on them in order to prevent further complications or infections.